1. Field of the Invention
This invention relates to improved organic compositions containing organic sulfonic acids and fluoride ion which are useful as stripping agents in removing polymeric organic substances, such as photoresists, from aluminized inorganic substrates.
2. Brief Description of the Prior Art
During manufacture of semi-conductors and semi-conductor microcircuits, it is frequently necessary to coat the materials from which the semi-conductors and microcircuits are manufactured with a polymeric organic substance which is generally a photoresist, i.e. a substance which forms an etch resist upon exposure to light. Subsequently, the polymeric organic substance must be removed from the surface of the organic substrate which is typically a silicon dioxide coated silicon wafer and may also contain metallic microcircuitry, such as aluminum, on the surface. Therefore, there is a need for improved stripping compositions which will remove the polymeric organic substance from the coated inorganic substrate without corroding, dissolving or dulling the surface of the metallic circuitry or chemically altering the inorganic substrate.
Prior art methods are known for removing such polymeric organic substances by the use of organic compositions containing phenol and linear alkylbenzenesulfonic acids, as exemplified in U.S. Pat. No. 3,871,929 (Schevey, Kremers to Allied Chemical, issued March, 1975) or containing linear alkylbenzenesulfonic acids and aromatic, aliphatic or chlorinated aliphatic and aromatic solvents, but not phenol, as disclosed in a pending U.S. Application Ser. No. 740,154 (Vander Mey to Allied Chemical, filed Nov. 8, 1976).
Relative organic compositions containing at least about 0.05% of anhydrous hydrofluoric acid as a stripping agent and organic solvents and solubilizing agents for the hydrofluoric acid, for removing paint from metallic surfaces, are known in the prior art, as exemplified in U.S. Pat. No. 3,335,087 (Keers to Pennsalt, issued Aug., 1967), and U.S. Pat. No. 3,335,088 (Mendell to Pennsalt, issued Aug., 1967).
Prior art inorganic stripping compositions for removing polymeric organic substances comprise aqueous sulfuric acid compositions containing at least about 300 ppm of fluoride ion to reduced metallic dulling and corrosion, as exemplified in U.S. Pat. No. 3,932,130 (Bennett, Brockington to Texaco, issued January, 1976), U.S. Pat. No. 3,654,001 (Mann to North American Rockwell, issued April, 1972) and U.S. Pat. No. 3,060,071 (Kinder to Allied Research, issued Oct., 1962).
However, the disadvantages of the above mentioned inorganic compositions in photoresist removal applications are that they tend to cause undesirable etching of the silicon dioxide substrates due to their high concentration of flouride ion. The above mentioned organic compositions have the disadvantages of either producing undersirable dulling of the aluminum surface by formation of metallic oxides or undesirable etching of the silicon dioxide substrate.
It is an object of this invention to provide improved organic stripping compositions which cleanly and efficiently remove organic photoresist materials from aluminized inorganic substrates, particularly aluminized silicon dioxide, without causing substantial etching of the inorganic substrate or corrosion and dulling of the metallic circuitry on the surface of the inorganic substrate, even after repeated use at elevated temperatures.
It is also an object of this invention to provide a method for removing polymeric organic substances from the surfaces of aluminized inorganic substrates, particularly aluminized silicon dioxide, without causing etching of the inorganic substrate or corrosion and dulling of the metallic circuitry on the surface of the inorganic substrate.